ath10k: define ath10k_debug_start/_stop as static inline

Otherwise if CONFIG_ATH10K_DEBUGFS won't be set we will
end up with multiple definitions and compilation failure
in each place the header is included.
Signed-off-by: Bartosz Markowski <bartosz.markowski@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath10k/debug.h

@@ -52,12 +52,12 @@ void ath10k_debug_read_target_stats(struct ath10k *ar,
 				    struct wmi_stats_event *ev);
 
 #else
-int ath10k_debug_start(struct ath10k *ar)
+static inline int ath10k_debug_start(struct ath10k *ar)
 {
 	return 0;
 }
 
-void ath10k_debug_stop(struct ath10k *ar)
+static inline void ath10k_debug_stop(struct ath10k *ar)
 {
 }